# 3.01 Introduction

In this section we will analyse motion in one dimension using graphs and equations. We will only consider objects moving with constant velocity or constant acceleration. The section below summarises the relevant parts of the previous sections and some equations that apply when velocity or acceleration are constant.

• Displacement (s) is straight line distance in a particular direction from a specific reference point
• Velocity is the rate of change of displacement with time v = Δs/Δt
• Acceleration is the rate of change of velocity with time a = Δv/Δt
• Displacement, velocity and acceleration are vector quantities - they have direction as well as magnitude
• The directional nature of vectors can be represented with + and - signs for one dimensional motion
• Instantaneous speed = magnitude of instantaneous velocity
• In this section we will consider most examples where initial displacement and time are zero therefore we can just write v = s/t
• When considering acceleration we will consider examples where an object may have initial velocity (u) therefore we will use a = (v-u)/t
• When acceleration is constant the average velocity of an object is given by vave= (v + u)/2
(i.e. the average velocity is the sum of the initial and final velocity divided by two)